Production of so from acid sludge



Jan- 21, 1936- J. M. RUMPLE PRODUCTION 0F SO2 FROM ACID SLUDGE Filed Deo. 2, 1933 2 S11eec,s-Sheerl l ATTORNEY.

Jan. 21, 1936. 1 M RUMPLE 2,028,725

PRODUCTION OF sog FROM ACID SLUDGE Filed Deo. 2, 1933 2 Sheets-Sheen'l 2 ATTORNEY.

si H u lsf the acid sludge from tion of petroleum described and blaiined in ful manner an SO2 Afurther diluted.

lPatented Jen'. 2i, A1.936

UNITED STATES:

PATENT OFFICE fraonuc'rroiv oF so, raum acm smoel;

James M. Rumple,

st. Leni., me.,

dan Chemical Construction Corporation, New York,

N. Y., a corporation of Delaware application December z, 193s, seran No. 'icones' 1s claim.. (c1. :za-117) 'rms invention vrelater to the production son from acid sludges fromthe sulfuric acid p tion of carbonaceous material, and more particularly to the production and utilimtion of SO: from the sulfuric acid puriiicahydrocarbons. J

In the past many attempts have been made to decompose theacid sludge from the sulfuric acid purincation of various materials, s uch as petroleum hydrocarbons, inlorder to recover a gas containing SO;- whichcan be utilized either by reoxidizing SO2 to SO: or in other ways.

, and it is only of moderately high strength since it" is diluted with the combustion gases used in heating the retort. The gas is then cooled to condense out water vapors and some of the condensable hydrocarbons. The `remaining hydrocarbons have to be removed if the gas is to be used for producing sulfuric acid Vby the contact process because of acid mist troubles which result when hydrocarbons are burned in the converter with the formation of water. moval, hydrocarboncombustion furnaces have been included inthe circuit as described in the copendlng application of Ingenuin Hechenbleikner and William Mast, Serial No. 693,136, filed Ocjtober 11, 1933.'- This modied processresults in a very pure S02 gas but since the combustion of hy drocarbons requires additional air the gases are rt has been round that these Hechenbleikner processes operate most effectively on sludges having a low oil content. However, even-with low oil sludges the SO: gas after purication is not of great strength.' When high oil sludges are treated )by the Hechenbleikner processes the amount of hydrocarbons which are not condensed is relatively high beca and this inist is not comp etely condensed so that a considerableportion of the. hydrocarbons which have a boiling point above the condensation tem.- perature remain in the gas stream in the form mew, Serial No.

' through the primary the l'ftumple process -heat exchangers.

ties encountered in handling high oil sludges.

In order to eiiect thisre-l an oil mist is formed-f ly with a resulting er ane mist peru-aes. hee'niadeit dimeuu to utilize the Hechenbleikner processes on' high oil sludges without further modifications.

Onemodiiled process is described and claimed" in the copendlng application of Frank J. Bartholo- 679,023, led July 5, 1933. Accordingto this modiiication of the Hechenbleikner process high oil sludges are subjected to preliminary distillation or stripping in stillswhich results in a considerable removal of hydrocarbons, lo'

the residual sludge being of about the same composition as low o il sludges which can be .eiiectively used yin the Hechenbleikner processes. This combined process, however. requires additional vapparatus and the character of the residual sludge will, or course, vary.with variations in the type or.

sludge fed. Theproblem of dilution has also been attacked l by recirculation of the heating gases as described and claimed in the copendlng applications of Gilchrist and Rumple, Serial No. 701,138 illed December 6, `1933 and Rinnple Serial No. 701,137 illed In these processes the gases kiln are rccirculated either through heating stoves or These processes result in the production of a relatively concentrated SO2 gas and obviate to a considerable extent the dimcul- They ar'e, however, more diilicult to operate and in the case of Rumple care must be taken to prevent deposition of solids in the heating stoves or heat exchangers. These processes'also require somewhat more complicated equipment than in a straight Hechenble er process and they repair Just as large a decomposition kiln which in the case of a large plant may be up' to 35 or more feet in length.

Y According to the culties involved in handling high oil siudg'es, or in fact sludges ofA any composition, are entirelyl eliminated. A gasof great strength is. produced and the apparatus is simpler and of greater capacitythan in the original Hechenbleikner proc- 45 ess.l The present invention'dependson the use of non-gaseous'heating media in an internallyy heated kiln. 'Ihese non-gaseous heating media 'may be of theanost varied kind, such asheated metal balls, heated sand, hot molten metals, such 50 as molten leid, molten salts and the like. The heating medium and sludge are caused to ilow into a kiln or other closed vesseland to mix intimately, the heating taking place very rapidcombustion 4furnace or in 25 llresent invention, the difenormous capacity from .rel- 5 5 burning, as described in Mast application, diluting with gases from a sulfur or ore burner as described in application of C. B. Clark, Serial No. 671,647, led May 18, 1933, etc. It is alsoposslble in the case of certain sludges which produce a relatively small amount ofuncondensable hydrocarbons, to eliminate puriilcation altogether because the amount is too low to cause any difllculty. Thus, the chief problem connected with the utilization of SO2 gases from acid sludge or similar material, is avoided and simple and economical methods of puriilcation can be employed without unduly diluting the purified gases.'

The great strength or the sc as obtained by the present process likewise permits the utilization of the s Oz gases in processes for which the Y Hechenbleikner processes would would be less suitable. Thusffor example, if it is desired to reduce the SO2 gases the copending application of C. B. Clark, Serial No. 675,973, led June 15, 1933,- the greater strength of. gas obtainable by the present inveny i particularly the sulfur collectors and permits higher recoveries described in the application above referred to, fthe presence of hydrocarbons within limits is not a detrimeht, but-on the contrary an advantage as it reduces the amount of Vfuel necessary. While it is an advantage `of the present process that hydrocarbons /can be removed to a very large extent .by simple condensation, it should be appreciated'that it is not necessary to run the process Vsolas to remove a maximum of hydrocarbons. On the contrary, by-keeplng the condensers at a suitably elevated temperature, it is possible to `retain a considerable amount of hydrocarbons w ch is advantageous in the production ofsulfur.

While the stronger gas and, when desiredglowf .er concentration of hydrocarbons obtainable by the present process,is of great advantage when used .with the normal types of purification, -it is a further'advantage of the present process that other methods of puriilcation can be effectively used with-` the present process which would not liquor of course be suitable with dilute gases. Thus, for example, the strong/SO2 gas obtained. by the present procabsorbed in water to form an SOz'liquor of quite reasonable concentration, for example, up to or even 'more From this the SO2 can be removed in a chemicilfpure state by heating when the SO: gas is to be used in the contact sulfuric acid process, the most usual eld of utilization, the S0: can

by blowing vair through it to form an SO: gas

strength of S02 gases the probsimpllt0 sulfur, as described in I permits ,erable not in many cases be strippedfrom the liquor having the required concentration of SO2 and oxygen for optimum results in the contact sulfuric acid process. This gas, which is entirely pure except for the presence of requires only drying before passingsthrough the converter. A gas of such high purity is very advantageous. In the first place it can be-used at existing platinum contact acid plants for the gas is of course free of catalyst poisons, and even when employed in conjunction with modern vanadium contact acid plants which are not poisoned, acid of extraordinarily high purity is obtained; a difllcult problem in the ordinary Hechenbleikner process because the presence of -hy drocarbons; in the gases passing through the drying tower tend t2) contaminate the acid and of course any other acid soluble impurities contained in the gases will likewise act as contaminants. I prefer, therefore, to use the ab' sorption and stripping method for purifying the gases after removal of eondensable-water and hydrocarbons and in combination with this method of purification my-process showsits -greatest effectiveness, but it should be understood that the process isin no sense limited to any partlcular method of puriiication nor, for that matter, to the utilization as of the SO2 gas in the contact sulfuric acid process.

' The heating media may be of three general f types, molten metals, solids of relatively large particle size such as iron and finely divided solids such as sand. When molten metals or other molten materials-having a suillciently high boiling point to be useful as heating media, are employed the coke which is formed by the decomposition of acid sludge an which has the same desirable characteristics as the coke produced in the straight Hechenbleikner process is easily separated from the heating medium. 'Ihis recovery of the co e r use as fuel and in many installations where such coke is salable, constitutes an advantageous modification. When finely divided solids such as hot sand, are employed, the coke farmed contains the solids intimately admixed with it. It is possible in such cases to remove the coke by suitable means, when hot sand is employed 4it is generally prefto remove the coke from the sand but to burn the coke in' contact with the sand in order sludge.

methods of separation? and permits a verysimple method of heating the sand. It has, however, Athe disadvantage of consuming all vof the coke which y in salable present in an amount greater than that actually requiredto heat the sand. .'Ihe respective advantages and disadvantages of these two methods some moisture,l

in the decomposition of eliminates screening or and which usually is depend in considerable measure on the economic conditions and on the plant installation. In every casethe skilled engineer will adopt the modinca.-

tion best suited for the particularfplant and it is an advantage of the presentinvention that it is `applicable to a wide number of conditions and the best arrangement can, in any case, be chosen.

In the drawings Fig.` 1 is adiagrammatic elevation partly in section of lan installation utilizing hot sand as a heating medium; and

Fig. 2 is a diagrammaticelevationv partly in section of an installation utilizing heated steel balls as the heating medium.

In the drawings in Fig. l the sludge decomposition kiln is 'shown at the kiln is very much smaller than a kihi of comparable capacity' .in a straight' Heclienbleikner I, it being noted that evolved pass out through process. In fact the kiln may in some cases be less than one-quarter as long as is needed in the standard Hechenbleilmer process. Hot sand at about 1500 F. is fed into the kiln by means o1 the screw 2 and at from the tank 3 by means of the pump 4 into the kiln where it mixes with hot sand as the kiln revolves. It desired, the sludge inlet pipe may be water cooled to prevent plugging because oi' coke formation in the pipe. The proportion of sand to sludge may vary with different sludges. I find that very satisfactory results are obtained when the proportion is from 301' sand to l of sludge to 4 of sand to 1 of sludge, but other proportions may be used. 'I'he decomposition of the sludge takes place very rapidly and a' ilne mixture oi' sand and coke is produced which -ls discharged at about 400 F. through the coke discharge 6. 'I'he gases gas outlet 5. The sand and coke mixture falls on to a conveyor 'I on which it is transported to elevator 8 which raises it and discharges into heating ignited by the pilot fiame 2| and burns. I'he combustion gases pass up the stackIIl. The combustion of the cokeintimately mixed with the sand heats the latter to red heat and the sand is then discharged through the valve I I- into the course be utilized in any suitable mann'er ce g Gal

S02 content may thesludge pass through a baiiied air .out .of the liquor and screw feed where it ows into the kiln. The screw does not extend to the opening into the kiln so that sand piles up and acts as a gas seal. gases passing out through the stafck I may of by means of a waste heat boiler (not shown) uThe gases evolved from the decomposition of condenser I2, thence through a condenser coil I3, cooled by a spray ofwater from the spray I4, and nally through a scrubbing tower I in which a con` stant circulation of water is effected by the pump I6. Fresh water is introduced into the system through the-valved pipe I'I. In the condensers and scrubbing tower hydrocarbons are very eifectively condensed since the gases are undiluted by combustion gases a or no oil mist fo course is saturated oils ow out from the bottom of the two condensers through the pipe the oil is drawn oi through the pipe and the water containing dissolved SO2 is continuously removed through a syphon pipeand, if desired, the

be recovered by stripping, preferably by means of. heat. S02 solution and oil which is formed in the scrubber I5, are continution. 'I'he water, which of .ously drawn off from the circuit through a valved pipe which connects to the pipe I8.

The scrubbed gases leaving the tower I5 through the pipe 22, iow up through an'absorbing tower 23 counter to a spray of cold water or dilute SO2 solution. Practically all of the SO2 is absorbed, thesmall residue of fixed gases being sucked on.' from the top of the tower the blower 24. The SO2 liquor thus formed iiows out of the bottom of the tower through the pipe 25 into an SO2 liquor tank 26. From the tank 26 the SO2 liquor ispumped by the pump 21 into the tojof a stripping tower 28 where it flows downover packing in countercurrent to a stream of 'air introduced into the bottom of thetower through the air inlet29. 'I'his airs'trips. most of the SO:

Atower throughthe pipe 30. The stripped liquor iows out of the bottom of the tower through the pipe 3| into the weak liquor tank 32 where, if desired, make-up water may be introduced through A pump 38, a cooler 31 kiln 9 where then coke is absorbed in an absorber 43 in the the waste gasesvpassing out through a stack 44.'

` 'I'he hot This is normally eifected such as .usually two absorbers absorber and stripper, d accordingly there is little with SO2, and the condensed I8 into the separator I9 where passes out at the top of the` the valved pipe 32. Make-up water is required as the amount of water vapor carried on' by the blower 24 and by the stream of air in the stripping tower, is greater than the amount oi' moisture in the gases leaving the scrubber I5.

' 'I'he SO: gas which is mixed with the proper amount of air for conversion into SOiby the contact process, leaves the tower 28 ina highly puriiied form but containingmf course, a considerable strong sulfuric acid which may be for instance, of 93% strength., The acid is circulated through the dryer from the acid tank 35 by means of the the temperature at the desired point so as to being provided to maintainy ensure emcient drying. The dehydrated gases are then sucked by the blower 38 andforced `through vthe converter 39' which consists of a ng portion 49 and .a heat excatalyst contai changer 4I. converted gases after leaving the heat exchanger through pipe 42 are then usual manner,

The circulation of acid-'which may be of 98% or greater strength, is from the tank 45 through the pump 46, absorber 43, and back through the cooler 41. 'I'he absorption of SO:4 in thevabsorber 43 requires the addition of water to the system.

by causing a the weak acid from the the absorber circuit through tlie valved pipe 48. Similarly, a portion 'of absorber circuit can be the dryer circuit through the valved pipe 49. Valved draw-oli acid from the tanks acid or stronger acid.

are arranged in series.

portion of dryer circuit to ow into pipes v5 IIand Ely-serve to draw off, 35 and 45 respectively, depending on Whether the system is to produce 93% If oleum is to be produced the strong acid from the caused to flow -back into It should be understood that the particular method of purifying tion. It is a veryeiective SO2 gas of high purity for but any other method may the contact process,

shown in purely conventional form and it shouldV be ,understood that the invention may' be used SO2 gases by means of an does not limit the invenmethod of obtainingbe used which proves y'desirable under the lparticular uconditions of Vav with any suitable design of converter, dryer orabsorption equipment. The modication in Fig.`2 utilizes metal balls instead of .hot sand, otherwise the apparatusA is the same and similar ence numerals. heating. furnace. sludge kiln I, where they mix with the acid sludge introduced from .the sludge tank' 3 in the same manner as in Fig. l. tact between sludge and balls should`normally b e somewhat greater, which may be obtainedeither .by using a longer kiln or by cutting down the rate of feed. The reason for the slightly longer time 'of contact lies in the fact that the balls do not give off their heat instantaneously and a nite period of timeis' required for the balls and the 'sludge residue to com to a` uniform temperature.

However, the .time of con parts bear the-same referv The hot iron balls from the bail 52 are caused to flow into the 75 troleum 117 The coke and balls fall on to the conveyor 1 and are then lifted by the elevator 8 from which they are discharged on to the screen 53 through which the finely divided coke passes, being removed The balls freed from coke fall into the bin 5 where -they gradugases from the burner 5l in the furnace 52. The balls are therefore preheated before they actually enter the furnace and contact with the flame. Thecombustion gases, after passing through the balls, -leave through stack 51. e

The gas evolved in the kiln is purified in precisely the same manner as in Fig. 1 and is of -substantially the same composition.

The amount of balls required will vary between 3 and 4 times the weight of sludge treated and since the amount of coke produced contains more heat units than is usually required, a very marked .10 saving vin fuel is obtained over the process shown readily salable, this is an importantl economy and for this reason I prefer` to use this modication of the invention although Y it should be understood that in its broader asreheating the heattransferring medium. In general the temperatures of hot sand o r hot metal balls will be approximately the same as the total heat to be transmitted to the sludge depends on the temperature of the heating the weights are the same; sion of the metal balls are very slight and because of the fact that these balls absorb the heat of the burner very effectively, there is notn as great a 35 temperature evolved,in contact with the furnace walls as may be the case when sand and coke are burned as in Fig. l, especially where the amount of coke is greater than that needed to supply the requisite amount of heat. y

In both the iigures of the drawings the SO2 gas is shown as utilized in the contact sulfuric acid process.. 'I'his constitutes the most important commercial utilization in most cases, but it should be understood that any other utilization of the SO2 is included,such asidesc'ribed above, the production of liquid SO2 where there is a market for the same,- the production of sultes and bisultes, the oxidation of SO2 in chamber plants `and the like In every case the great strength of the gas permits utilizing equipment at maximum 'efliciency and the full advantages of having a high concentrationof S0; are enjoyed irrespective ofwhat particular method of utilization of the gas is employed.

The drawings are purely diagrammatic in nature since the exact mechanical construction of the apparatus usedvin the process does not form any part of the present contrary any suitable types of apparatus may be used. Likewise structural details have been -omitted for the sake of clearness but it should be .understood that in an actual plant the skilled engineer will usel well known apparatus with all of the accessories whichv are necessary to its operation. Thus, for example, insulation of kiln, furnace and other units is vomitted'for the sake of simplicity,

umts operated at high temperatures will be in. .sulated in the usual manner. Similarly the converter is shown in purely 'diagrammatic formV and without any accessories. Y

The present invention has ticularly in conjunction with the treatment of sulfuric acid sludge from the purlcation of pedrocarbOns. Naturally. of course, this pects the invention includes either method of l The losses from abranv as the production of sulfuri solids, the temperature invention and on the but of course in an actual plant,

been described paris equally applicable to the treatment of sludges obtained by the sulfuric acid purification of other carbonaceous materia1s,such as, for example, the

purication of coal tar fractions and the like. The invention is also applicable to the treatment of other SOl containing materials which can be thermally decomposed to yield gases containing What I claim is: 1. A method of decomposing acid sludge from the sulfuric acid purification of hydro-carbonaceous material which comprises thoroughly mixing the sludge with a stream of a highly heated,`

heating medium, the temperature and the amount ofthe heating medium being such a's to decompose the sludge to a carbonaceous residue with evolution of S0: free from HzS, continuously removing the SO: gas evolved from the reaction zone and removing the carbonaceous residue and the heating medium.

2. A method of decomposing acid sludge from the sulfuric acid purification of hydro-carbonaceous material which comprises thoroughly mixing the sludge with a stream of highly heated solids, the temperature and the amount of the solids being such as to decompose the sludge to a carbonaceous residue with evolution of SO: free from HnS, continuously removing the SO: gas evolved from the reactionzone and removing the carbonaceous residue and the soli 3. A method of decomposing acid sludge from the sulfuric acid purification of hydro-carbona-- ceous material, which comprises thoroughly mixof highly heated,

such as to decompose continuously removing the S02 gas evolved from the reaction zone and removing the carbonaceous residue and the heating medium, separating the carbonaceous residue from the heating medium and reusingthe heating medium after reheating.

4. A method of decomposing acid sludge from the sulfuric acid purification of hydro-carbonaceous material, which comprises thoroughly mixing the sludge with a stream of highly heated and the amount of the solids being such as to. decompose the sludge to-r a carbonaceous residuewith evolution of SO2 free from HzS, continuously removing the SO: gas evolved from the reaction zone and removing the carbonaceous residue from the solids, separating the carbonaceous residue from the solids, and reheating and reusing the solids.

5. A method according to claim SO2 gas evolved is cooled to condense out water and-condensable hydrocarbons, and the SO: gas is then adjusted to a composition containing sufcient oxygen for the contact sulfuric acid process and an amount of hydrocarbons giving 'a hydrogen content less than 3 mg. per cubic foot and passing -the gas thus adjusted at reaction temperature over a contact sulfuric acid catalyst. 6. A method according to claim 2 in which the SO2 gas evolved is cooled to condense out water andcondensable hydrocarbons, and the SO2 gas is then adjusted to a composition containing sufcient Oxygen ess and an amount of hydrocarbons giving a" hydrogen content less than 3 mg. percubic foot and passing the gas thus adjusted at reaction temperature over a contact sulfuric acid catalyst.

'1. A method of decomposing acid sludge from l in which the for the contact sulfuric acid proc- .and removing the SO2 from the sulfuric acid .ceous material which comprises thoroughly mixgas is absorbed, the'liquor thus formed. v

8. A method of decomposing acid sludge from the sulfuric acid purification of hydro-carbonathe carbonaceous residue and the solids,cooling the SO2 gas evolved to condense out water and the stripped so, liquor is used at 12. A method according to claim the solids are metal balls.

`13. A method according to claim 4 in which the solids are metal balls,

14. A method according to claim 7 in which the solids are metal balls.

15. A method according to claim 4 in 2 in which are sifted to separate the carbonaceous residue from the solids and the solids are passed in countercurrent to a flow of combustion gases and then into contact with the sludge stream.

16. A method according to -claim 4 in which the heating solids are metal balls and the balls and carbonaceous residue are continuously discharged from the reaction zone, are sifted to separate the carbonaceous residue from the balls, and the balls are passed in countercurrent to a separated and the solids are reheated and reused.

ow of combustion gases and then into contact with the sludge stream.

JAMES M. RUMPLE. 

